Lead is a widely used environmental toxic agent and there is a great need for practical, sensitive methods for detecting its early biological effects in man. It is currently agreed that neurobehavioral changes might be the earliest indicators of subclinical lead intoxication. However, it is not yet clear which neurobehavioral dimensions are most likely to be effected by lead. The present study proposes to examine behavioral indicators of lead neurotoxicity, some of which (such as performance tests) have proven to be sensitive in the assessment of the earliest functional central nervous system changes produced by lead. It is also proposed that the speed and quantitative characteristics of eye movements (as detected by electro-oculographic methods) might be an important addition to the battery of neurobehavioral tests. The speed and characteristics of saccades are known to be influenced by neurotoxic agents, particularly when they act selectively, as lead does, on the cerebellum. Elevated blood lead levels and zinc protoporphyrin (ZPP) have been shown to be correlated with lowered performance test scores. It is also expected that these two biological indicators of exposure will be correlated with a decrease in the speed of oculomotor behavior. Performance tests (including the electrophysiological evaluation of visuo-oculomotor performance) might prove to be simple and objective methods for the early evaluation of central nervous system functional changes produced by this environmental toxic agent.